This invention relates to a bicycle hub, and more particularly to an improvement in a bicycle hub of the quick-release type which is designed so as to be detachable from and re-attachable to a pair of fork ends rigidly secured to bicycle frame tubes. This type of bicycle hub is typically utilized in a road racing type bicycle which is so designed that a wheel can be instantly replaced with a new one when a tire is punctured or the wheel is damaged during the race. The quick-release type hub is also utilized in a collapsible type bicycle which is so designed that, after roughly disassembled, it can be packed in a bag or the like container so as to be easily carried into a car, a bus, a train, an airplane or other private or public transportation apparatus.
The conventional quick-release type hub, as disclosed for example in Japanese Utility Model Publication No. 51-10525, generally includes a stationary tubular hub axle, an axially slidable center spindle passing through the hub axle and having at one end an enlarged cylindrical head in which an oval through hole is formed extending transversely of the longitudinal axis of the spindle, a stationary cap member capped on the enlarged head of the slidable spindle and having a circular through hole extending in the same direction as the oval through hole, an adjusting nut mounted on the other end (threaded end) of the spindle, and a cam lever having a non-eccentric annular flange and an eccentric actuating shaft which extends through the oval through hole as well as the circular through hole in such a manner that the eccentric actuating shaft cooperates with the oval through hole of the spindle head while the non-eccentric annular flange of the cam lever cooperates with the circular through hole of the stationary cap member, so that, when the lever is turned, the spindle is axially moved back and forth through the eccentric motion of the actuating shaft. The hub also includes a pair of lock nuts (a first lock nut and a second lock nut) each of which is mounted on the opposite ends of the spindle, respectively, so as to cooperate with the adjusting nut and the enlarged head of the spindle in order that one fork end can be tightly sandwiched between the second lock nut and the adjusting nut while the other fork end can be tightly sandwiched between the first lock nut and the spindle head. The adjusting nut serves to adjust the clamping forces applied to the fork ends.
In the conventional quick-release type hub as above-described, the eccentric actuating shaft is directly associated with the enlarged cylindrical head of the slidable spindle and thus, turning motion of the cam lever is directly transmitted to the spindle head so as to urge the spindle axially. Naturally, when the cam lever is turned by a certain angle from its clamping position toward its releasing position, a distance between the spindle head and the first lock nut as well as a distance between the adjusting nut and the second lock nut are simultaneously enlarged in dependence upon the angular motion of the lever. As a result, when the cam lever happens to get in contact with something, for example a certain portion of a competitor's bicycle during the race, the hub is unexpectedly disengaged from the fork ends. Especially when the hub of a front wheel is disengaged from the fork ends of a bicycle running at a high speed, a serious accident may happen.
Accordingly, it is an object of the invention to eliminate the above-discussed disadvantage in the prior art devices.
Another object of the invention is to provide an improved quick-release type hub for bicycles which promotes safety by preventing unexpected disengagement of the hub from the fork ends.
A further object of the invention is to provide an improved quick-release type hub for bicycles which maintains its clamping function with respect to the fork ends for safety's sake until a cam lever is turned beyond a predetermined angle.
These and other objects, advantages, and features of the invention will become more apparent from the detailed description given hereinafter in connection with the accompanying drawings. It should be understood, however, that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will be apparent to those skilled in the art from this detailed description and illustration.